Comanche leans on the trunk of a beater gray two-door coupe, walkie-talkie in hand. Slung over his shoulder is a radio receiver tuned to the police scanner.

"There's people who only do pollos, others only do drugs," Comanche begins, offering us a round of beers.

"And if you lose a backpack with drugs, or something like that, they kill you," adds Juan, a young coyote, or foot guide, who works for Comanche. "They" being cartel bosses.

There's a noise to the right. It's a nightwatch popping his head out from inside the building of el Diario de Sonora, a local newspaper here in Nogales, Sonora, Mexico. The guard smiles, waves at Comanche, and ducks back inside. Comanche grins, sets the walkie-talkie down, and cracks a beer.

There are more discreet places to meet a cartel boss and one of his coyotes, who guide migrants across the desert, than in front of a newspaper office. The original plan was a cantina in the center of town.

But plans change.

*

It is a cool and clear February night. A dog barks in the distance. Comanche's radio crackles.

We're standing in the unpaved parking lot of el Diario in an out-of-the-way barrio of Nogales, which shares the border with Nogales, Arizona. Ambos Nogales (Both Nogales), as the binational community is known, is a major port of entry along the nearly 2,000-mile border between Mexico and the United States.

We'd come to this region to spend some time with Comanche, a Sinaloa cartel plaza boss and Daniel, one of Comanche's human traffickers, or polleros. They agreed, through an intermediary who communicated with both of them using WhatsApp, the encrypted messaging service, to meet with us. The meeting was part of a Motherboard investigation that reverse engineered a stream of remotely-guided smuggling, whereby polleros like Daniel cross pollos ("chickens"), as migrants are known, over the border via cheap, pay-to-use phones known as burners.

Agents with US Border Patrol call this crossing tactic "remote control." It's the next step in the never-ending technological arms race between cartels, which control both drug and human trafficking in Mexico, and authorities, with migrants caught in the middle.

What we found in that investigation is that burners, which flood the borderlands, make crossing safer for many migrants and business more efficient for smugglers. As a result, human trafficking has never been more personal.

They're almost invisible, which seems to be the point.

We knew Daniel, an uncharacteristically outspoken twenty-something pollero, had taken to remotely guiding pollos across the border line from the vantage of a hilltop apartment complex in downtown Nogales, Sonora. He was always proud of being smuggler and would show us how remote control works. We never did meet him though. Daniel was shot dead in the street, not far from the border line, days before we arrived in town.

In his place, Comanche introduced us to Juan. As we'd learn, Juan harbors a distrust of phones in the hands of his pollos because he thinks US borderland law enforcement officials are tracking their movements. This paranoia suggests a further evolution in smuggling tactics in light of US Border Patrol and other borderland law enforcement agencies using controversial cell-site simulator tools like StingRays and Triggerfish, which gather phone data by emulating cell towers, in real-time criminal investigations.

Juan agreed to talk with us about why he thinks border authorities are using those signals intelligence tools to also monitor pollos and coyotes like him. Juan and Comanche, who both use smartphones, also agreed to explain how the cat-and-mouse nature of human trafficking and efforts to thwart it is playing out on both sides of the border. This is the first time either of them have spoken with media.

*

All that separates America from Mexico, and that drives the human trafficking business, is a slatted iron fence between 15 and 30 feet tall throughout Ambos Nogales. Further out in the desert, there isn't even a wall, per se. Just waist-high wire fencing.

Which is where people like Comanche and Juan come in.

Comanche heads up one of the Sinaloa cartel's smuggling cells in Ambos Nogales. He's a plaza boss, meaning he's in charge of smuggling operations in a given patch of the cartel's turf here. He is likely not el jefe, the top boss. But we know Comanche oversees at least part of Nogales plaza proper. He's 47.

Then there's Juan, whose name has been changed to protect his identity and who's been crossing pollos for one year. He lights a cigarette, cracks his beer, and spits in the dust. He is 25.

We first met Comanche and Juan earlier that day at a McDonald's near downtown Nogales, Sonora. They defy most narco stereotypes. No fancy boots, no white chinos, no cowboy hats. They don't arrive in a BMW, but rather lurch up in Comanche's beater.

They're almost invisible, which seems to be the point.

Comanche is maybe 5'6" and taking on the shape of an aging boxer: round belly, a stiff, see-sawing gait, and thick, worn fingers, like a rancher's, that pull you in close when he shakes your hand. His short black hair is greying in the temples and mustache and he has a broad forehead and brown eyes that open wide when he emphasizes a point. Comanche wears a grubby grey and black sweater over an orange polo and his jeans are frayed at the heels of his Pumas. He regularly hocks phlegm and has an almost impossibly raspy laugh.

In other words, Comanche is not your average cartel boss. He does not present himself as such. But you start picking up on certain things.

Comanche will talk about mi gente. My people.

He says things like: Tengo a la gente en un viaje. I've got my people on a trip to the US.

Or, "There's always going to be pinchepollos." Bloody migrants.

And, "People? They are just a pinchebillete." A bloody small expense.

It gives the impression Comanche has been around long enough to have some standing in the cartel hierarchy. However, it is unclear exactly how long Comanche has been in organized crime, or if he's always been affiliated with the Sinaloa cartel. He says he's been living here in Nogales for 13 years.

He is apparently a man of many roles, according to our fixer, Luis, a freelance reporter who has followed illegal trafficking and the cartels in Mexico for years. Luis first met Comanche last year, at which time Comanche said he was working in some capacity for the Policía Judicial, a special investigation unit. Comanche says he also owns an underground bar in Nogales that opens at 3 AM—would we like to come by?—and that recently he's been working with el Diario. The press badge he shows us expired in 2005.

Juan is just a kid next to Comanche. He is maybe 5'8" and ganglier and more aloof than his superior. He has a wisp of a mustache, a buzzed head, and wears jeans, Pumas, and an orange hoodie. He keeps a black baseball cap low on the brow. Every so often Juan picks at braces lining his upper teeth. He has sad, brown eyes that stare into the middle distance when he's not talking, which is often.

Illustration by Che Saitta-Zelterman

Juan crosses 15 to 20 pollos every week, he explains. He started crossing migrants at the urging of a friend he no longer speaks with, and doesn't seem to get much advanced warning about jobs before it's time to go. A lot of times, Juan tells us, he just runs into his bosses on the street. And they tell him, Let's go.

He and his pollos start at a remote spot "far away" from Ambos Nogales, Juan explains. He doesn't say exactly where, but it's apparently far enough outside the city that there is no proper "wall." Only a meter-tall wire fence that acts as a vehicle barrier, over which he crosses three or four people at a time. Juan does the trip without a map or GPS. He's committed the passage to memory.

"I've learned it really well," he says.

But it's still easy to get turned around in the dark. Many crossings take place under cover of darkness, especially in the warmer months, when temperatures can reach 100 degrees Fahrenheit during the day. At night, everything starts to look the same.

"I kind of follow my instinct," Juan says.

Best-case scenario, it's a three-day hike north through the desert to a pre-arranged drop-off site on the American side, Juan says. That's where another pollero in the smuggling chain rolls up in a car, the migrants jump in, and off they go.

It's all tightly coordinated.

"They calculate the time," Comanche explains. "They will be there at some time and day, and that's it."

It's another three days as Juan retraces the journey. This time he's alone. He sleeps in the hills and hides in the canyons. If he gets lost or injured all he has is himself. He can't call 911 because Juan doesn't even carry a phone while crossing.

Pollos are charged between $3,500 and $4,000 for the trip, according to Juan. (He says he doesn't smuggle drugs, only people, but that smugglers can earn $1,800 for successfully carrying a load of illegal narcotics into the US.) Juan is the last link in the Sinaloa's local smuggling chain, beginning with recruiters who move pollos from safehouse to safehouse until, finally, they get to where Juan is along the line. He says he gets $1,400 per head for a successful trip.

"People are very suspicious here. They don't use cell phones."

The migrants Juan crosses, he tells us, likewise don't carry phones during the trip. He and his bosses will turn off and round up migrant's burner phones for fear of cell-site simulators now hanging over la migra's dragnet. When high-tech trumps low-tech, go no tech, the thinking goes.

Besides, Comanche adds, bosses on the line don't want to risk an "infiltrated pollo" using a phone to snitch on them. So, by the time Juan joins his pollos their mobile devices have already been turned off and confiscated.

There is one crossing route, however, in which migrants do carry phones, according to Juan and Comanche. That's the route "through the line," so to speak: walking through the Ambos Nogales pedestrian queue with a fake ID provided by a pollero. In these cases both Comanche and Juan say migrants will travel alone and are picked up at a McDonald's on the US side. This route comes at a steeper price. Crossing through the checkpoint costs $5,500.

But otherwise, Juan says his bosses out at the desert crossing point are untrusting of all phones. He says they don't even use WhatsApp to communicate securely among themselves. It's a curious admission because we've been communicating with Comanche, and by extension Juan, exclusively via WhatsApp.

Illustration by Che Saitta-Zelterman

The distrust of phones Juan and Comanche speak of shouldn't necessarily be extrapolated to mean all migrants, smugglers, and plaza bosses are paranoid of phones, don't carry them, or both. Too many people on both sides of the border told us otherwise.

It does makes sense that certain polleros and coyotes would now be concerned about authorities potentially monitoring cell activity, insofar as the specter of la migra's dragnet does loom large as guides like Juan cross migrants over the border and into the US. And what he and Comanche tell us about pollos' phones being confiscated isn't far off from we've heard of migrant's phones sometimes being turned off and temporarily held by polleros and coyotes, who then return the phones to their clients after the crossing is complete.

But are borderland authorities tracing the phones of migrants and low-level guides on the move? Not likely.

Local, state, and federal law enforcement agencies operating in the borderlands do utilize controversial signals intelligence technologies known as StingRays and TriggerFish, which emulate cell towers and trick phones into giving up data. But these tools, officials say, are only deployed in urgent criminal investigations, not to locate groups of pollos being led by a coyote. Also, StingRays, TriggerFish, and the like only work when a phone is turned on.

In other words, Juan and his superiors out on lalínea have small reason to distrust phones for fear of pings blowing their cover. If anything, what they should really be worried about is good, old fashioned "sign cutting," whereby borderland authorities track and assess footprints, upturned rocks, bent twigs, and other small environmental disturbances in hopes of nabbing crossers and prosecuting their guides. Paranoia isn't anomalous in the broader view of modern human trafficking. But being a borderline technophobe is.

What's not out of the ordinary, though, is Juan's very real fear of all the other uncertainties lurking right over the line. In 2013, one of the deadliest years on record, 168 bodies were recovered in Arizona's desert frontier, according to the Pima County Medical Examiner's Office. As they cross the border, low-level guides like Juan and people like Chino, a 33-year-old undocumented Mexican migrant living in New York City who spoke at length with us about illegally crossing the border four times, face the threat of injury, dehydration, being kidnapped, extorted, raped, tortured, murdered, or simply "disappeared."

Juan tell us he's particularly worried about bajadores. That's local slang for "steal," to literally "take down." Say you're a coyote like Juan and you're deep into the wilderness, dozens of miles from civilization, and a bajador jumps you and steals your money and your people. Guess who has to pay up to your bosses? That's if the bajador doesn't just kill you after robbing you and taking your pollos.

"If a bajador don't want to leave you there, they kill you," Comanche says. "They only see money. Even if there's people they only see money."

Comanche catches sight of something outside the McDonald's. Shifts his neck for a better look. He relaxes a beat later and sips his Coke. Then his phone pings.

*

The border fence is visible from the Pancho Villa, a cantina in downtown Nogales, Sonora. It's a weeknight and the streets are mostly empty. We meet Comanche and Juan here around 10 PM. We order a round of beers. They go with Tecates, we get Indios.

After some small talk the guys admit they don't feel comfortable. The hotel next door is a known safe house for pollos waiting around for polleros, according to Comanche. There's rival cartel scouts everywhere, he says, and you can never be sure who's listening. He's also worried about a levanton. Being kidnapped.

Time to move.

Gif by Che Saitta-Zelterman

We finish our beers, leave the Pancho Villa, and agree to meet somewhere farther off the main drags, maybe in a vacant lot near our hotel. So we start heading in that direction. They lead the way in Comanche's beater, we follow in Luis' rental car, and—that car behind us, following a little too close. Are we getting boxed in?

We drive along in silence. Are we being lured into a trap? Probably not. But then what if the cartel, someone other than or above Comanche, finds out that we are talking to him and Juan? Also, does Comanche have a gun on him? Luis suspects he might.

And what if the police show up? In Mexico, that's not always a good thing if you're not a cartel member. Comanche told us there is an arrangement between the Sinaloa and local cops in Nogales. Police roll up? Just say the password. No hassle.

"I have to find a way to do something else"

The police do not roll up as we settle in outside el Diario. Juan's taking a leak on a tree while Comanche, really playing the elder now, explains to us that the human trafficking business is just not what it used to be in Ambos Nogales.

"It's slower," Comanche admits. It used to be that he would see polleros walking right along la línea. "You'd look and say, 'Ay guy, a lot of pollos.' You don't see that anymore."

"People are afraid," Juan adds. So is he. It's good money, sure. Good enough to support his kids. But it's just too risky. "I have to find a way to do something else," he admits.

Until then, he will see himself in the pollos he crosses.

"They are people with needs, like me," Juan says. They're poor. He would never leave any of them behind. "It would feel ugly" to do that, he says. One time, he claims, he carried an older woman who'd injured her leg for a couple miles.

"Almost everyone is from here," he says. "From Mexico. We are the same people."